This project is a continuation of an effort to better understand an important class of chemical induced oral sensations, namely those associated with astringency from tannins, acids and complex salts. These sensations are poorly understood, yet are important components of food flavor. Furthermore, since the interactions of astringent substances with saliva impart a kind of "artificial xerostomia," understanding of astringency and its influences on other oral chemosensory stimuli may provide insights into the oral chemosensory function of patients suffering from dry mouth. The present application proposes fundamental psychophysical research into quantitative and qualitative specification of human perceptions derived from astringent stimulation. Previous work has shown the potential importance of astringent subqualities of oral drying, roughing and tightening, and individual assessment of these three attributes is a unique approach in this project. The proposed experiments include 1) studies of effects or stimulus volume, duration and buffering on perception of astringency, 2) assessment of qualitative descriptors used by individuals to describe these sensations via multidimensional scaling, 3) investigation of mixtures of astringent materials and their perceptual additivity, 4) studies of additional compounds and structure-activity assessment of polymeric tannins, and 5) specification of interactions of astringents with tastes and with irritative oral trigeminal stimuli in model systems. The research will provide basic information about the relationship of perceived astringency to fundamental physical variables. In broader terms, it should further clarify the interplay between oral chemical and tactile sensations and provide insights into the role of saliva in oral protection, lubrication and the modulation of flavor sensations.